(a) Field of the Invention
The invention relates to a perforation device for making roll of plastic bag with an opening and a perforation line on each bag.
(b) Description of the Prior Art
As shown in FIG. 1, a conventional roll of plastic bag which linked by perforation line (B) is made by a sealing device and a perforation device, each bag of material roll is formed by a sealing line (A) and a perforation line (B). To use the roll of plastic bags in prior art, each bag needs to be torn off along the perforation line to form an opening for package, this manual process involves much increase of packaging time, waste of manual work, and the most important, the roll could not be incorporated with automatic weighing and packaging machine or a conveyor for automatic package in a mass production line. A latest prior art has been disclosed in U.S. Pat. No. 6,086,524 to Martin, filed on Nov. 14, 1996, entitled xe2x80x9cRECLOSABLE STORAGE BAG AND METHOD FOR MAKING THE SAMExe2x80x9d. The patent disclosed a reciprocal cutting unit device 223, two bolts with springs and two compressing blocks 163 and 165, and a serrated cutting edge. The storage bag provided by that patent involves a piece of reclosable string, the string being incorporated as an integrated marginal part of the bag outside a margin of the storage bag.
The storage bag disclosed by Martin includes a string, and is not applicable for production of a roll of plastic bags, therefore, it is not suitable for automated operation involving weighing and packaging machine or conveyor packaging line.
The objective of the present invention is to provide a perforation device for making roll of plastic bag with an opening and a perforation line on each plastic bag. The perforation device comprising a cutting unit, an anvil unit and an expanding board. The cutting unit comprises a holder, toothed blade and a specified number of compressing blocks, the expanding board expands the inner of material plastic bag to a specified space, the toothed blade then cuts into the material bags to make an opening and a perforation line on the material plastic bag. The roll of plastic bag made by present invention is ideal for incorporated with an automatic weighing and packaging machine or a conveyor on a production line as a high efficiency packaging system.
A preferred embodiment of the invention is described below to achieve the objective of the present invention.